Control of electromagnetic devices



Ap 1942- A. R. VAN c. WARRINGTON 2,279,349

I CONTROL OF ELECTROMAGNETIC DEVICES.

Filed May 16, 1940 Fig. 4.

lnventpr; Albert F2 van C. Warring: on,

by His Attorney.

Patented Apr. 14, 1943 UNITED "STATES PATENT OFFICE common or smc'rnomcssnc nsvrcss Albert 1:. van 0. wminmn. Waiiinglord, n,

assignor to .General Electric Company, a corporation of New York Application May 16, 1940, Serial No. 335,518

4: Claims.

My invention relates to improvements in the control oi electromagnetic devices and more particularly relays having movable armatures, and the principal object of my invention is to accelerate the response, such as pickup, drop-out, or both, of such devices.

Refinement of structure, sensitivity of response,and high speed of operation in certain complex relays, such for example as distance relays, frequently limit the number of contacts on the relay to less than may be required in certain more advanced protective systems, such for example as those oi the so-called carrier pilot type. To circumvent this paucity oi contacts, auxiliary devices, such as electromagnetic'relays, may be used. However, such added elements necessarily increase'the time required for a given cycle of operations; This may add to the delay in opening a circuit breaker or it mayretard the operation of other devices and lead to a false operation of the protective relay cycle. In order to minimize this added time delay, the auxiliary relays have been operated at voltages several times the continuous duty voltage for which they are designed. While this may be reasonably sat- I isfactory from the standpoint of accelerating. the

of the overvoltage, to damage the more or less relay structure but also to the system since the I intended cycle of protective operations is disrupted anda system fault may not be cleared in time to avoid damage to the system.

In accordance with my invention, I minimize the time of operation of electromagnetic devices by means embodying thefintroduction of transient electric current quantities whereby to quicken the response of the devices on pickup, drop-out, or both. Pickup is, oi course, understood in the art as that value of the electric quantity which will cause operation of the device, and drop-out is the return or reset of the device to itsoriginal position, that is before pickup, when the electric quantity assumes some other value usually less than the" pickup value. Since auxiliary relays are generally energized from the station battery, another object of my invention is to provide accelerated pickup and drop-out action for electromagnetic devices which are energized from direct current sources.

Other objects of my invention will appear in more detail hereinafter.

My invention will be better understood from the following description when considered in connection with the accompanying drawing, and its scope will be pointed out in the appended claims.

In the accompanying sheet of drawings, Fig. 1 illustrates diagrammatically an embodiment of my invention for accelerating the drop-out of an electromagnetic device; Fig. 2 illustrates diagrammatically an arrangement for accelerating the pickup of an electromagnetic device; Fig. 3

illustrates diagrammatically an embodiment of my invention for accelerating both the pickup and drop-out of an electromagnetic device; and

Figs. 4, 5 and 6 are wave diagrams .explanatory of the arrangements diagrammatically illustrated in Figs. 1, 2 and 3, respectively.

In the embodiment of my invention shown in Fig. l I have illustrated means for accelerating the dfop-out of an electromagnetic device, such as a relay ll, having an energizing winding H by means of transient current operation. This is accomplished by connecting in series relation with the relay winding ll suitable current limiting means, such as a resistance 12, and across the series related relay winding and resistance suitable current limiting means, such as an inductance Lil. The two parallel circuit branches thus formed are arranged to be connected to a suitable source of direct current,-not shown but indicated by plus and minus signs, through suitable circuit controlling means which may be, for example, the relatively movable contacts .H and I! of a protective relay. While the relay II is shown as having only one pair of contacts it, it is well known to the art that such auxiliary relays may be provided with as many sets of contacts as are desirable.

In this embodiment of my invention it will be obvious that, by suitably proportioning the ohmic values of the winding ii, the resistance i2 and the inductance IS, the current in the winding II will, when the contacts I and I5 are closed, increase exponentially from the zero value at a to the constant value b when the steady state condition is reached whereupon the relay II will be actuated. However, when the contacts I4 and I! are opened, the current will I decrease from the value b and overshoot the zero value to some value c in consequence oi the time constant of the closed circuit comprising the winding ii, the resistance i2 and the inductance Subsequently, when conditions havereached a steady state in this circuit, the currentwill return to the zero value a. It will be obvious that, when the contacts I and I5 are open, the current, which was flowing in the winding II and its series related resistance I2 and would tend to continue to flow in the closed circuit including the winding ll, resistance l2 and the inductance I3, is opposed by the inductive discharge current of the inductance l3. In consequence of this, the drop-out of the relay II is accelerated to produce a quicker action by the transient induced in the closed circuit. In some cases the resistance of the relay winding H may be such as to render a separate resistance l2 unnecessary.

In the arrangement shown in Fig. 2, upon closure 0! the contacts I and IS, the resistor I2 is arranged to be momentarily bypassed by suitable means, such as a condenser l1. With this arrangement, it will be apparent that, uponclosure of the contacts II and IS, the condenser 11, while it is being charged, in effect short-circuits the resistance I2 so that the full voltage of the direct current source is momentarily applied. However, since the .by-passing is not done by rethe winding II, the greater the overshoot c.

What I claim as new Letters Patent of the United States is:

1. In combination, an electromagnetic device having an energizing winding, a direct current circuit comprising two parallel branches including in one branch said winding and in another branch an inductance, the ohmic values of said winding, and inductance being such that when said circuit is interrupted the now of current in said winding is quickly suppressed.

2. In combination, an electromagnetic device having an energizing winding, a resistance connected in series relation with said winding, a source of direct current, a switch for connecting said source across said series related winding and resistance, means for accelerating the pickup oi. said electromagnetic device when said switch is closed comprising a condenser connected across said resistance, and means for accelerating the drop-out of said electromagnetic device when said switch is opened comprising an inductance connected directly across said winding and said resistance.

3. In combination, an electromagnetic device having an energizing winding, means for limiting the flow of current in said winding, 9. source a of direct current, circuit controlling means for lay contacts, which may fail, the full voltage is not maintained on the relay beyond its safe time rating.

Fig. 5 shows the current wave form starting at the zero value a, when the contacts I4 and ii are closed, and rising quickly to a value d which overshoots or is in excess of the steady current value b which is reached by way of a damped oscillation as indicated. when the contacts I4 and I! are open, the current decreases again to a zero value, as shown. The increased eflective effort for pickup of the relay l0 over the arrangement shown in Fig. 1', whereby th action is accelerated, is indicated by the area edfg within the full and dotted line curves in Fig. 5 to the left of the line 3:: where the relay operates. To obtain a similar increased eiIort by operating at above normal voltage rating would require a current flow, such as indicated by the dash and dot line ehk. As is obvious, this would require about twice the current flow in the relay winding and would increase the hazard not only to the winding but to the contacts l4 0! the protective relay.

Thus with the arrangement shown in Fig. 1 a normal pickup and accelerated drop-out is eitected, whereas with the arrangement shown in Fig. 2 an accelerated pickup with a normal dropout is obtained; In accordance with my invention, I combine the arrangements shown in Figs. 1 and 2 in order to insure both an accelerated pickup and an accelerated drop-out. In the arrangement shown in Fig. 3 the inductance I3 is connected across the relay winding II and the series related parallel connected condenser l1 and resistance II. This arrangement provides three parallel branches in the direct current circuit with thephmic values of the winding ll, resistance l2, inductance ll and condenser l'I-so proportioned as to provide the desired initial and final transient effects in order to obtain the accelerated pickup and drop-out. l While I have shown and described my invenconnecting said source across said winding and current limiting means, and means for quickly retarding the flow of current in said winding when said circuit controlling means is operated to disconnect said source.

4. In combination, an' electromagnetic device having an energizing winding and a circuit comprising three'parallel branches including'in one branch said winding and a condenser, ina secsaid source.

tion in considerabl detail, I do not desire to be limited to the exact arrangements shown, but

seek to cover in the appended claims all those modifications that fall within the true spirit and scope of my invention.

and branch said winding and a resistance and in a third branch an inductance, the ohmic values of said winding, condenser, resistance and inductance being such that when a' source of direct current is connected to said circuit a predetermined momentarily increased flow oi current appears in said winding and when said source is disconnected the flow of current in said winding is quickly suppressed. i

5. In combination, an electromagnet comprising an armature and an energizing winding, current limiting means connected in series relation with said winding, a source of direct current, circuit controlling means for connecting said source across said series related winding and current limiting means to cause the pickup or said armature, and means for accelerating the drop-out 01' said armature when.said circuit controlling means is operated to disconnect said series re- J limiting means from' lated winding and current 6. In combination, an electromagnet comprising an armature and an energizing winding, current limiting means connectedin series relation with said winding, a source of direct current, circuit controlling means for connecting said source across said series related winding and current limiting means, means for momentarily lay-pessing said current limiting means when said circuit controlling means is operated to connect said source 0! direct current across the sries related winding and current limiting means whereby to accelerate the pickup of said armature, arid'rinductive current limiting means for accelerating the drop-out of saidarmature when said circuit controlling means is operated to disconnect said source of 'direct current from said series related winding and current limiting means.

7. In combination, an electromagnetic de and desire to secure by having an energizing winding, a'resistance connected in series relation with said winding, 9. source of direct current, a switch for connecting said source across said series related winding and resistance to cause the pickup of said electromagnetic device, and means for accelerating the drop-out of said device when said switch is opened comprising an inductance connected directly across said series related winding and resistance.

8. In combination, an electromagnetic device having an energizing winding, a source oi direct current, circuit controlling means for conne ting said source across said winding, and means for quickly retarding the flow of current in said winding when said circuit controlling means is I operated to disconnect said source.

9. In combination, an electromagnetic device' having an energizing windin a resistance connected in series relation with said winding, 9.:

source of direct current, a switch for connecting said source across said series related winding and resistance, means for accelerating the pickup oi said electromagnetic device when said switch is closed comprising a condenser connected across said resistance, and means for accelerating the drop-out of saidelectromagnetic device when said switch is open comprising an inductance connected in parallel relation with said winding.

ALBERT R. VAN c. WARRINGTON. 

